Cbl-c ubiquitin ligase activity is increased via the interaction of its RING finger domain with a LIM domain of the paxillin homolog, Hic 5.

Therapeutic Approaches

Abstract

Cbl proteins (Cbl, Cbl-b and Cbl-c) are ubiquitin ligases that are critical regulators of tyrosine kinase signaling. In this study we identify a new Cbl-c interacting protein, Hydrogen peroxide Induced Construct 5 (Hic-5). The two proteins interact through a novel interaction mediated by the RING finger of Cbl-c and the LIM2 domain of Hic-5. Further, this interaction is mediated and dependent on specific zinc coordinating complexes within the RING finger and LIM domain. Binding of Hic-5 to Cbl-c leads to an increase in the ubiquitin ligase activity of Cbl-c once Cbl-c has been activated by Src phosphorylation or through an activating phosphomimetic mutation. In addition, co-transfection of Hic-5 with Cbl-c leads to an increase in Cbl-c mediated ubiquitination of the EGFR. These data suggest that Hic-5 enhances Cbl-c ubiquitin ligase activity once Cbl-c has been phosphorylated and activated. Interactions between heterologous RING fingers have been shown to activate E3s. This is the first demonstration of enhancement of ubiquitin ligase activity of a RING finger ubiquitin ligase by the direct interaction of a LIM zinc coordinating domain.

Authors

Ryan, Philip E; Kales, Stephen; Yadavalli, Rajgopal; Nau, Marion M; Zhang, Han; Lipkowitz, Stanley;

Keywords

  • Cell Line
  • HEK293 Cells
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins/ metabolism
  • LIM Domain Proteins/ metabolism
  • Protein Interaction Domains and Motifs
  • Protein Interaction Mapping
  • Protein Structure, Tertiary
  • Proto-Oncogene Proteins c-cbl/ metabolism
  • Proto-Oncogene Proteins c-cbl/ physiology
  • RING Finger Domains
  • Receptor, Epidermal Growth Factor/ metabolism
  • Two-Hybrid System Techniques
  • Ubiquitination

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